Wire chief&#39;s test circuit for telephone systems



Sept. 2, 1924. v 1,501,075

C. E. LOMAX WIRE CHIEFS TEST CIRCUIT FOR TELEPHONE SYSTEMS Filed May 18. 1921 4 Shuts-Sheet 1 WIRE Gym/=3 HEAD SET.

Elaranue ELamax C. E. LOMAX Sept. 2,1924.

' WIRE CHIBFS TEST CIRCUIT FOR TELEPHONE SYSTEMS Filed May 18 4 Sheets-$heet 2 .Tnu5n UF EZarEmE EL nmax Sept. 2 1924.

C. E. LOMAX WIRE CHIBF'S TEST CIRCUIT FOR TELEPHONE; SYSTEMS Sept. 2 1924.

-C. E. LOMAX WIRE CHIEFS TEST CIRCUIT FOR TELEPHONE SYSTEMS Filed May 18. 192

4 Sheets-Sheet 4 Em Qxmt mmoikwm Em- Elarsnua ELumax Patented Sept. 2, 1924.

UNI- ED CICARENCE E. noMAX,o-F CHICACo IJnnIiNd'Is, rssng imt q 'EILECEERI COMPANY, OF CHICAGO; I'L'LIN'OIS, A CORFORATTCN 0F r-Lnmols.

pplication means? 18;

To all whomkz't may concern:

'Be it known that, I, Gninnrton E. citizen of the United States" of America,- and a' resident of Chicago, Cook County, and State of Illinois, have invented Certain new and useful Improvements in- Wire" Chiefs Test Gircuits for Telephone Systems, of which the following is a specification.-

The present invention relates in gene'rah to-wire chiefs test circuits for telephone sys t'ems, but more especially to test circuits" of this kin'dwvhich are adapted for use in automatic telephone systems; and the oldje'ct of the invention briefly stated is to revise and refine the Various circuits used so as tomake them-more efiicient and p-raC-' tical. The'app-aratu's employed an'd' the va r-ious' features of the invention will be d scribed fully hereinafter, reference being had to-theaccomp anyingdr'awings, in which the system is illustrated by mean-s of theusual circuit diagrams:

Before'taking up the drawings in detail, afew general statements, relating to the system'as a whole, will be made: Although thefeatures of the invention are applicable to systems of different sizes-it is assumed that we are dealing with a- 100,000-line systeni,'--wl'iich is divided into ten separate main ofiices of 10,000 lines each, theseparate offices being so interconnected with trunk-lines asto form an integral system: The-testing of the'lin'es in the'va'rious ofiiees is assumed: to be done from one point by one or} more wire chiefs. There are'tenseparategroups of trunk lines, allgroups being multiplied" between the" wire chiefs desks, and each group extending to adifferent m'aLinofiibfe'. Each wire 'chief, therefore, may obtain d-irectaccess with any one of the-said main' oflices', merely by selecting atrun'k line" in the proper group. 1 1

Referring now to the drawings, lfi O'I'dBl to" enable the circuit-s'to be readily understood, Figs. 1, 2 and 3 should bearranged in order, with the corresponding linesatthe ends thereof in alignment,-an'd Fig; 4 should be placed directly under Fig. I; When laidout in this manneig-Figs: L to 3,- inelusive, show all the equipment-neces saryv for a- Complete connection from the" Siifir'l 4 76,5371

wi'rfe dhif s desieto "a =-stibs'ribei sflifie ifiliioh it: is desired to" test; 4; showsse'me ofthe equipmfefit at the complti int o 'verific'a tion operator-s pesitidng-rby mean's of which thecomplaiiitpera r can obtain access to' the testswitchesesueh as are" shownin- 2 and-3; v thunderi g-first the means by which the" wire chiefextends a connectionto' asub-'- seribers lineg-the outgo in trunk terminates thew'i're Reefsd'e's h key" K l igs 1, to which ""ire cl'i'ie'fs common "test'and' operating circuitsare In-utipled; This trunk l'ine'= rep-innume al-t' the other end metre-switch E;- termeda test dis tributor, which is oca tec l iri on'efiftliema'ino'fli'ees" of the" system: The' test" distriliiit'or- E is" a-- vertical and rotary switch of the Wellknown- Strowge'r' type having 100 sets of bank'- contaets arranged ten horizontal rows, or levels.v The circuits of this switch are shown c0'Inpflete and will be"? deseribd inful l'hereinaifter;

The test cbrineeter selector F, Fig ais a" switch? of the Strewger' type nearer-1tdiffers from the test} distributor E part-i'eularly in having-only a single" lev'elof bank O0I1lfi5 t$i It will be understood fr tim thisthat the switclthas eta-1y movement onlyt an'd that; the 'verfiibil ma net ai'nd'those' parts which have to do only with tlie' ver t-ic'al' mojvenfre'nt ?of the switch beeinit-ted lit maybe'mentioned also th at niece-mental Contacts 122 are arr-a;irged so as te closeon the-first rotary step I of the switch rather thanon the vertical step as is usuelly the" case.-

Tlfe test} connector H"; is" also strew'ger; ve'rtioai rotary switch: lithas 3 the fiill 100-cent sets and so-f a r as 'ts' n'ieiehanie'al construction is concerned} is sen-11in to the testdistributor It will be understoodthatthe sr'rbscribe'rs" lines in thesjy'ts'tem'- are divided i'nto rottps of 100"lin'es each; in" acce'rdance with" the" Capacity of the connector: sw ches which are ordinarily used for completing local connections: In eVeryIOO lin'e'iI-nit, in--addi--' tion to the" 10 'or 12 10691 connectors vi'liic-h are ordinarily provided, there is neness connector'saelr astheijt fi een'neetor-H, the lat ter" c'ornie''ct oi sw itch-berng 'e filth-sit er} for 1 the use of a wire chief or a complaint operator in testing the subscribers lines. One of the subscribers lines of the group to which the connector H belongs, is shown at the extreme right of Fig. 3, and extends to the automatic telephone substation A.

The reference character C indicates an individual line switch of the well known rotary type, which is provided for the use of the subscriber at substation A in extending his line, when calling, to an idle first selector switch in the regular exchange trunking system.

The arrangement of the trunking between the test switches will now be explained a little more fully. Considering a fully equipped office of 10,000 lines capacity, there are 100 groups of connector switches and as a test connector is provided in each of these groups, there are 100 test connectors. Now, since the test distributors have 100 contact sets and are directively controlled in both their vertical and rotary movements, all of these test connectors may be reached by way of the test distributors in the particular office under consideration without any intervening switches. There will be perhaps three or four of these test distributors, such as the test distributor E,, Fig. 2 which have common access to all of the test connectors in the ofiice. This is the usual arrangement digits instead of five, the extra digit being,

for a straight 10,000 line office or exchange. It happens quite often, however, that, in offices which include a number of party lines, in. addition to the individual or private lines, fourth selectors are inserted between the third selectors and connectors in those major groups which are used for the party line traflic. This is especially true of systems in which a plurality of groups of con nectors, .each of which sends out ringing current of a different character, have access to the same. 100 lines. In such cases, in order not to reduce the capacity, the party line subscribers are called by means of six the fourth which controls the operation of the fourth selectors in selecting the proper group of connectors. The drawings show an arrangement of test switches which is adapted for use in a composite office of the type described which includes both individual and party lines. The test distributors have direct access to all of the test connectors which are located in the individualline connector groups, but on the particular level, or possibly levels, which are assigned to the party lines, the test distributors have access to test connector selectors such as the test connector'selector F, which is shown in Fig.

Each connector selector in turn has access to the test connectors in ten different connector groups Consideringnow the means by which the complaint, or verification -operator extends the switch I), however differs from either of these as will be pointed out fully hereinafter.

The switch D, with regard to the trunking arrangement, plays the part of a first selector and accordingly trunk lines, of which i the trunk line comprising conductors 3236, inclusive is one, extending to a main ofiice or exchange, are terminated in each level of bank contacts, accordingto the usual practice.-.

The system, having been described generally, will now be described in connection with a detailed explanation of the operation of the various circuits. For this purpose it will be assumed that the wire chief wishes to test the line of substation A. It is first necessary for the wire chief to obtain connection with a test distributor in the particular office in which the line of substation A terminates. To do this he operates a key which is associated with a trunk line extending to the particular main oflice in which the a a line of substation A terminates, thekey K",

for example, the associated trunk line being idle as indicated by the unlighted condition of busy lamp L Upon operating, the key K places ground on the conductor 36 at spring 39, thereby lighting busy lamps before the other wire chiefs. This ground potential extends by way of conductor 36 to test contact 247, Figure 4, and its multiples in the banks of the test distributor selector repeaters thereby guarding the seized trunk line against intrusion in the usual manner.

As a further result of the operation of key K it connects the wire chiefs test conductors 30 and 31 in multiple with the test conductors 32 and 33 of the trunk line associated with the key K by way of the working contacts of springs 15 and 18 of said springs,

resting contacts of armatures 21 and 23 and core. As a further result at the operation of 7 key K the springs 14 and 19 place the following bridge across the operating trunk conductors 34 and 35: from conductor 35, by way of spring 19 and 1ts working contact, spring 5 of key K and its resting contact,

normally closed contacts controlled by spring 3 of key K, spring 4 of the same key audits resting contact, normally closed contacts a controlled by spring2 resting contact of step. At the end of the vertical movement,

spring 6 of key K and the said spring, left hand winding of electropolarized relay 7, and the working contact of spring 1470]": key K and said spring, to conductor 34. 7 Conductors 34 and 35 terminate in the upper and lower windings of line relay 430i test distrilnitor E, passing through relays 41v and 42. ,Accordingly, the said relays 41 to 43,

inclusive, energize.

Electropolarized relay howeveiyhis not energized,at this time, because the flux gen erated in the left hand winding coincides in direction with the flux formerly vshuntedj from the armature by the core associated with the said winding. Each core now acts a magnetic short circuit for the flux gener-j ated in the other. a t

Returning now to the linerelay 43 of the test distributorE, upon energizing, the said relay closes a circuit for release relay 44 which, upon energizing, opens a point in the circuit or release magnet 64 at armature62, at the same time prep ring a circuit forthe vertical magnet 99. 1

T he wire chief now throws his key'K in such a direction as to operate the springs 2" and :thereby inserting his calling device and head-set intothe control circuit. I The wire chief may now manipulateth dial-oi his calling device in accordance with the-first digit o-fthe desired number, whereupon the line relay 43- is deenergizedya corresponding number. of times and, upon each deenergizatwn,-closes the following ClI'CIlltffrom ground,.by way of armature 60 and. its resting contact,iarmature' 62 and its working contact, off normal springs 70 and 68, slow acting series relay '45, and vertical magnet? 99, to batteryi -By the operation of the ver-o tical magnet, the, shaft and wipers are raised stepby step until the latter stand opposite the desired level of bankvcontacts. The slow acting-relay 45' is energizediin series with the vertical magnet and at its armature .63

maintains the circuit of the vertical magnetj intact act'ter the of? normal sprlngs have shifted as they do upon the first vertical slow acting relay 45 deenergiz'es and transters the inipulsing'circuit from the vertical to the rotaryflmagnet.

The wire chief now turns calling devicefor the second dig-it where upon the line relay 43'is deenergized a corresponding number of timesiand at'each deeuergization completes. the {following yci'rr; cuit: from ground, byway of armature-} and its resting. contact,'arn1ature 62 and its," working contact, ofi' normal springs and,

69, armature 63 and its resting contact, and slow actingrelay 46,. to battery, A branch ,luctant in energizing. depends upon whether the test contact 96 with which the tests wiper '90 is in engagement isbusy oridle. If it is busy it has. a ground potential on it and a circuit isclosed the are his of this cirjcuitiextends;by way of armature n77 andits" resting contact, armature 82and itsresting'contact, and rotarymagnet. 100 to battery, ;*;By, the operation of the rotary' magnet, th'e shaft :and Wipers are rotated stepmby step untilthe lattenfinally come to rest on the ,desiredset-of contacts, assumed in this. case to be the contacts .93 to 98, inclusive. The, slow acting re1ay46 is energized in multiple with thef'rotary, magnet and atarmature 72 closes the following circuit for the slow acting relay47 from ground, by way of working contact of armature 61 and .said arrnature, resting contact of armature g f4'9andsaidarmaturacarmature 72 andits workin contact and slow actin rela 47 to battery; Upon energizing, relay 4'] closes a busy test, CHCLIltgat armature and at .ar-

matures- 85-and8 6jopens', the heavy test,con-' ductors so as to prevent interference :with

the trunk lines over which the wipers pass.

At theendof the rotary movementthe slow acting; relay 46-deenergizes and at ar-,

mature 72 opens the circuit of relay 47 and: at the same time completes a circuitffor switching relay 49 by wayof the, Working 'contact 'ot armature 76 and said armature, f and switching relay 49 tobattery. Switch-' f ingrelay 49, on account of its inductive] winding and stiff adjustment is slightly re i'roin ground by way of theisaid test contact,

The operation now test wiper90, armaturej83 and its resting;

-contact-,,.,armature 75 and itsjworking contact, upper winding 0']; busy relay 48, and

relay 47, to'battery. Relay 48 is {energized over this circuit and relay 4'? is maintainedenergized. Upon energizing, relay .48 opens i'tlle circuit of switching relay 49, at armature,

7 9, before the said relay has had time to ent ergize; connects, at armature 80,.a,leadfrom the busy; signalling machine'B tothe lower operatlng conductor35,:thus glving'the Wire i'chiefan audible busy ,signahand at armature 78 closes the circuit of reversing relay' 40. Upon energizing, relay 4O reversesthe operating conductors 34 (and 35jas regards their connection with line-relay 48, .This

relay and accordinglythe fiuX was-shortcircuited-,= so to speak, .asnone of 11; "was forced;

to flow out through the heel piece and ar mature of the relay but rather{ flowed through the two cores andassociated yokein trolled by'armature 123, relay 117, and r- I an tary magnet 119 tobattery. By the operation of the rotary magnet, the shaft and wipers'are stepped around step by step until the latter finally come to rest upon the de sired set of bank contacts, assumed in this c'ase tobe theco'ntacts 137 to 141, inclusive. Relay 117 is energized in series with the rotary magnet and being slow acting retains its armatures attracted throughout the rotary movement. Upon energizing, relay 117 shifts conductor 104:, at armature'126, from ground by way of its resting contact to direct ground by way of its working contact closes a circuit for the upper winding of relay 118 at armature "125; and, at armature 124, serves to maintain the circuit of the rotary magnet 119-intact after the energization of relay 116 which'occurs upon the first step of the switch, they said relay being energized in series with the release 'magnet 120 which,

on account Of'its comparatively small number of turns and the high resistance of relay 116 is not energized at this-time. Relay 118, upon energizing, opens the heavy test conductors at armatures 127 and 131; "disconnects wipers 133 and 134:,- at arm'atures 1 17 and 128, respectively and preparesa locking circuit for itself at armature 129. At the end of the rotary movement the slow acting relay 117 'deenergiz'es and, at armature 124, shifts the operating'circuit from the'rotary magnet 119 to the operating lead which extends to the resting contacts of armature 147'; opens the original energizing circuit of relay 118 at armature {and at armature 126 extends the conductor 10 1' to battery by way of the resistance R From this point the operation depends upon whether the test connector H is busyTor idle. Assuming'first that it is busy, in which event test contact will'be grounded,relay 118 remains energized,'and busy'relayl8 in the switchE, the lower winding of which is now connected to conductor 104, isenergi zefd I in series Witll'I'QSlStitIlCQS R and, upon energi'z'ing, gives the calling 'wlre chlef'the' be fore mentioned visual and audible busy si-gnals' The calling wire chief,-upon notin'g the before mentioned busy signals, may-release the connection and call again'la'ten but we shall assume that he decides to wait until the test connector Hbecome's idle, c

' A question may now arise in'the minds of some as to whether or not 'anothe'r test distributor which lands on a multiple of'the bank contacts 93 98, inclusive, will be. given a'busy signal and denied connectiongin vi w "of the fact that "direct ground is nowremoved from conductor 104: and "battery by way of resistance R placed thereon. In an- 1 swer to this question it may be saidthat the resistances'o'f the lower winding'or relay 48 v urn are so proportioned-"as to "allow the'multiples of test contact-9'6 to remain to the calling wire chief.

-We shallnow assume that the't-est connec-l tor H becomes idle. 1 When the ground potential disappears fromconductor 140, relay give connector H time to restore' itself. to normal condition, 'and at'armatures'127 and '118 deenergizes,somewhat slowly so as to 131 connects up the heavy test conductors;

connects up the wipers 133' and 134; at arm? tures 147- and 128 places ground on test con tact 140, at armature 129; and,at armature 130, removes battery from eonductdrlO i and places ground thereon; In the' test distributor Eybusy relay 18 deenergiz'e's as soon 'as the resistance R'is' disconnected from clonductor 10 1 thereby removing the before men tioned visual and audible busy signals, and the wire chief is apprised thereby that he may continue the" operation. a

Assuming now that the testconnector. H

is idle-when called as hereinbefore explained,

' relay 117 deenergizes at the end of the rotary moyement and opens the circuit of relay 1-18 whlch deenergi'zes with the previously described results. It may be stated that, while relay 118 is slightly'slow in falling 'backso as to give the test connector H time to restore to normal, as previously pointed out, itis not slow enough to give a momentary false busy The wire chief may now; operate his calling device in accordance -with the next d git of the desired number, whereupon a corresponding number of impulses are sent from ground, byway of previously traced circuit, to conductor'103'and from thence, I

by wa of the working contact of armatiire 123 and sa d armature, armature 12 1 and 'its'resting contact, resting contact of armature 1 1T and said armature, wiper 133, bank contact 138, on normal springs and 163,

relay 156 and vertical magnet 158 to'batte'ry; the operation of the vertical magnet the shaft and wipers of the test con the end of the verticalmovement, slow act ing relay 156 dee'nerg'i'zes and transfers the operating circuit from the vertical'to the,

rotary magnet.

nector H are raised step by stepfu'ntil the 'with the vertical magnet and serveslto maintain the circuit of thelatter intact after the oil normal springs have shift-ed, 'as they doupon the first vertical step, At

The calling wire chief may now flnanipw late his calling device in accordance with the next and lastdigit of the desired number, whereupon the rotary magnet 159 of ,1 switeh'fi is-energized acorres ondingnum her of times. By the operation of the rotary magnet, the wipers 166 to 168, in clusive, are stepped around step by step until they finally come to rest upon the bank contacts 169 to 171, inclusive, which are the ones in which the line ofsubstation A terminates.

The operation. new depends upon whether the called line is busy or idle. If it is busy there is a ground potential upon test contact 170 and slow acting relay 16 in switch E, upon. falling back, completes the following circuit for reversing relay 40: from ground by way of test contact 170, test wiper 167, conductor 1-414, bank contact 13.9,wiper 134, armature 128 and its resting contact, conductor 102, bank contact 94, wiper 88, armature 81 and its working con tact, working contact of armature 74 and said armature, armature 71 and its resting contact, and reversing relay 40 to battery. Relay 4O energizes and an instant later slow acting relay d7 deenergizesy By the combined operation of relays 40 and 47, the circuit of re ay 40 is shifted so as to include for the heavy test conductors are connected with the called line at this time whether it is idle or not "and the wire chief need only operate the key K to connect his head set with the heavy test conductors and he may listen in and thereby ascertain the condition of the called line. In this case, as

before, when a line is called and found to be busy the wire chief may wait until it becomes idle when the visual busy signal is automatica ly extinguished.

Assuming that the line of substation A is idle when called or, which is practically the same thing, becomes so after being called, relay 4O deenergizes, slightly sluggishly because of the copper slug, when the-ground potential is removed from test contact 170, thereby'removing the visua! busy signal in a manner hereinbefore described, With relay to deenergized a circuit'may be traced from ground, by way of the workin contact of armature'58 and said armature, resting contact of armature 55 and said armature, and back over the previously traced circult to test contact 170,

and from thence, by way of private normal conductor 173, switching relay 180, and stepping magnet 182 to battery. It may be explained at this point that while relay 10 is slow acting it is only slightly so and that the reason for its being slow, is; to allow a predetermined time, sufficient to take care of differences in adjustment, for the switching relay of the called .line switch to fall back before the above traced circuit is closed for it by the falling back at the said relay 10. Switching relay 180 now energizes but the-stepping magnet. 182, is not energized on account of the high re-' sistance of the said switching relay. .Upon

energizing, switching relay 180 removes the bridge of .the line relay 181 from the called line but, on account'of a mechanical inter locking, device (not shown) between the armatures of the said relay and line relay 181, the armatures of relay 180 are operated only abouthalfway and consequently the wipers of the line switch are not con nected up.

, Having finished dialling, the wire chief returns the key K to normal position. It

will be noted that the heavy test conductors loo than that shown, we shall assume that the wire chief makes the necessary tests;

We shall assumenow that there is a repair man at the substation A making some necessary repairs and that the wire chief wishes to co-operate with him. In order to signal the repair man at substation A. the wire chief throws key K in such a direction as to project ringing current out over the heavy test conductors, thereby operating the bridged bell at the said substation. The. key K is now thrown in the opposite direction and springs 24; to 26, inclusive, are accordingly operated. The wire chief now'operates key K, thereby placing his head set in multiple with the heavytest conductors.

When the repair man at substation A answers, he may converse with the wire chief, talking battery beingsupplied to the transmittera at the called substation by way of imped-a-nces 37 and 38 and springs 24 and 26 and their working contacts. It willbe no ticed that with spring. 24 operated the condenser 29 is in series with the wire chiefs head set so as to insulate the latter from the direct currentswhich is flowing out to the transmitter at substation A. I

Assuming now that the repairman says that he has a fewmore repairs to make which will require only a short time, and that the ire h 1 d de to ho .up th m-inaction connects them to the upper and lower windings of rel y 1 Th wire teln t :ma-y new ,retulrnthegkey "K to normal and use E-the test circuit for testing tether lines while he is Waiting for there-pair man to signal that he is ready for line of substation A to :be tested. 1

It will bernoted that the hey K upon re- .turningzto normal position, lights the busy lalnp .L since there is .a ground potential on conductor 36 independent ,of the said key K v e V After the repair man has made -the neces sary repairs and is ready to signal :;the wire chief, he lifts the receiver at substation ,A' from the hook, thereby closing a circuit for relay 16, 11, which, upon operating. closes ,arcircuit ton-the lamp L at immature 17, The wire chief upon noting the lighted condition of lamp L knows that-ther.ep2 1ir manxdesires to converse with Accordingly he reoperates the key K and operates keys K and K so as to connect his head set in bridge ,of the test conductors and place talking battery .on the said conductors way of impedances 3 7 and .38. Ellie-wire chief now restores the key I .to norma position, whereupon the lamp L isextinguished and relays 16 :and 20 are ideenergized, and the heayy test conductors are connectedp again at armatures 21 and 23. ,Qbyiously the ,wire chieftand repair man may now-converse as before.

'We shall now assume that the wi zeachiet wishes to (test the line switch -C {to find out whether or not the said switch is amat uing properly. In order to do this the wire ch1e ;f .returns the key K to normal ,position -.thereupon removing the ,iinpedances 3.7 and 38 from in bridge of the test conductors '30 and .31 and replacing the shortcn'euit aro nd;

condenser 29 at spring 2%. The wire chief now operates the key K in such a direction as to separate the spring 5 ,from {its contact, thereby introducing the resistance new t e perat ng c r uit In the test distributor E, relay -=ll,.,b e.- tug margi a ly adjus ed, falls when th said r s tan e is ntre hwed into its ci ui b t relays 42 and L3 @2 9 not'da neta as t me inen ee e sieing,

lay 4 1 ,opens .thecircuit-of switching u'elay.

180 o t the line switch .0 and the sa d chiefs head set, :1ineyre1ay'181 c o e t- @Bmnfz m 1. 7 a cir i '-;for the switching relay 180 ;:and the stepping :rnagnet 182311 series, and at armature 18,6 connects the test Wiper 189tovthe above circuit at :a zpoin-t between t e switching relay and the ping lin r-enct. Tlhe operat on 1 depends upon whether the trunk line .up on which the wipers (of vthe lineqswitch are standing is h'usy or idle; PH it -;-is,- busy, the test contact with which the test lwiper 189 is ncasem n i am d d i hin e ay 1 is short Qircuited; 'a d e teeping magnet 18?, which interrupts its iow-ncircuit is ,eperated ,in :the manner ot a buzzer' to ,adyance the wipers step by step search of .idle "trunk line. "InQthe present case, however, -,we :may assume that the trunk iline upon which the wipers of the -l-ine switch arestanding is idle; That eing the case, the stepping agne 51 2 "is no t ,encl2gizecl because I o; the high resistance of the switching relay, abut the latter ,is'eni ergized,g1gounds the test wiper {at armature 1 discon nzcts..the line conductors 172 .antl..-174: from the winding of line relay 181 and tw n ground respectively, and extends sthe nnby way of \line wipers 188-;and 1.90 to the -upper and lower winding of the line-relayot a first selector switch. The line Iand release relays (not shown) of the saidese-lector immediately ienergize and ,the latter places ground on the release trunk concluctormthereby establishing the usual holding circuit [for the switching relay .180. It is obvious that the \wire chief .may .return the key .K to normal any time afiter th line aelay 18 1 has operated. From this point the operation may proceed in anyone of a member of ways, for example, wire chief may have a telephone (at his desk, and, assuming he has, he may call the number of aid teleph e a i h my find out whether or not (he is able .to operate the exchange switches tromthe line in question.

We shall now assume that the were chief desires to test the line of ca substation which terminates in the same level asgthe sline of substation A and in a Set of contacts that is farther around in the rotary movement of the switch -than the set in which the-line of substation A terminates, for example, the

li of substation A ay te m. Kate in the fiifi s or ontact i h velin case the wire chief desires to test another {l -11$ W iQh terminate in he sixth, Or-any of th iollowing sets in the same fil s 1, h

ma cetate-bis e liagn vi a; seesaw with the proper digit and thereby cause the rotary magnet 159 of the connector H to step the wipers 166 to 168, inclusive, around to the desired. set of contacts, the operation in this case being the same as that when the last digit of the number of substation A is called.

We shall. now assume that the wire chief desires to test a line which terminates in the banks of the connector H, either in a different level from that in which the line of substation A terminates or in the same level but in a set of contacts that has already been passed over by the switch wipers.

In order to release the test connector selector F and the test connector H without releasing the test distributor E, the wire chief operates the key K in such a direction as to separate the spring6 from its resting contact, thereby introducing the resistance R into the operating circuit. In the testdistributor E, relays 41 and 42 fall back when the said resistance is introduced into their circuit, relay 42 also being marginally adjusted but line relay 43 does not deenergize at this time. Relay 41, upon deenergizing, removes ground from the wipers 134 and 167 at armature 58, so that they will not interfere with the contacts over which they pass Relay 42. upon deenergizing, opens the circuit of release relay 115 of selector F at armature 59. Upon deenergizingrelease relay 115 opens the circuit of release relay 155 of connector H and at the sametime closes a circuit for release magnet 120. By the operation of the release magnet the shaft and wipers of switch F are restored. to normal position, the circuit of the release magnet being opened at off normal contacts 122 by the shaft when it reaches normal position. Obviously the relay 116 deenergizes as a consequence of the above operation.

In the connector H, release relay 155,,upon deenergizing, closes the circuit of release magnet 157, which energizes and restores the switch to normal position in the usual manner. It is to be understood that the wire chief may release the test distributor also by throwing the key I; to release position, for in this position spring; 4 completely opens the circuit of relays 414 inclusive, of switch v The wire chief now restores the key K to normal position, thereby short circuiting the resistance R and allowing relays 41 and42 to' energize again. He'may now operate his calling device in accordance with the proper digits and thereby cause the selector F and the connector H to operate again to give access to any line that terminates in the banks of the said connector. It is obvious that in case the wire chief desires to test a line that terminates in the banks of another connectorto which the selector F has access. he could do so equally well without releasing the test distributor E.

Having finished making the necessary tests, the wire chief returns the key K" to normal position, thereby IBITIOViH ground from the common conductor 36 whereupon the busy lamps in front of the other wire chiefs become extinguished and the trunk line is rendered idle to the automatic switches having access to it. As a further result of the operation of the key K the wire chiefs test and operating;' connuctors are disconnected from the test and operating conductors of the trunk line. whereupon. the relays 41-43, inclusive, deenergize. Re-v lay 43, upon deenergizing, opens the circuit of release relay 44 at the same time placing ground upon the operating conductor ex.- tending to the switches ahead, thereby operating); the test connector to cause it to step around another step. This, however, has no particular utility at this time. In addition to operating the test connector ELS'QXE plained, this ground on the operating conductor operates slow acting relay 46 inthe usual manner. Relay 46, upon energizing, closes the circuit of release relay 115 of switch F, thereby preventing its deenergzization as hereinbefore explained. Slowacting relay 47 is energized at this time in the usual manner, but its energization has no particular function during this operation.

Slow acting release relay 44 now fallsback,

thereby removing ground from the operatinc; conductor extending to the connector 'I-I. whereupon the rotary magnet of the said connector deenergizes. Slow acting relay 46, however, holds up for a moment. As a further result of the deenergization of relay 44, it opens, at armature61, the circuit of the slow acting relay 4'? and switching manner.

Returning new to release relay 44, as a. still further result of its deenergrization. it closes, at armature 62., a circuit for the release magnet 64. By the operation of the release magnet, the shaft and wipers are restored to normal position, the circuit of the release magnet being opened at ofl normal contacts 67 by the shaft when it reaches normal position. Slow acting relays 46 and 47 now fall back. All of the apparatus used by the" wirechief in making the tests is now'restored'to normal position.

It may be stated now that, in case the wire chief calls a line that terminates in a so called "straight line boardor a board in which there is only one group of connectors, the calling wire chief need only omit the digit used in the previously described case to operate the test connecter selector F. This 1s perfectly obvious in View of the fact that ,t-he'trunk extending to. the test connector in While there are six conductors in the trunk line leading to the test connector H, there are only five wipers-on the switch F and consequently only five bank contacts in each set;

91. of switch E, is used not only to send a ground potential ahead, to operate the release relay of the nextswitch, but also as a test wiper; Thatbeing the/case, conductor 148 has no utility whatever when the connector H is used in a party line board, but when the said connector is used in a straight line board the said conductor. 148

terminates in test contacts in the banks of the test distributors corresponding to the tributor E.

. We shall now assume that 1 a complaint, or

verification operator, whose head set is shown in Fig; 4, desires to call the line of;

substation A to find out Whether it is busy, idle, orf-out oforder. This is, done,usually,

only after someone has called in to the said operator and made a complalnt concerning the 'said substation. In-order to initiate such a call, the complaint operator throws a key associated with an idle trunk line, the key K .for example, the associated trunk line being idle as denoted by the unlighted con dition of the lamp L". Upon operating, key K -closes, at springv 262, a circuit for the busy lampL and its multiples in frontof the other operators, but does not close a cir-.1

cuit for the busy lamp L owing to the fact that the circuit of the said lamp is opened vby spring-262, at thls' time. As a further result of the operation of key K it closes a cir-' cuit for the right-hand or polarizing winding of the electropolarized relay 20.0, at spring 1 261. It is to be understood that relay 200 is 250 and 251 of the trunk line, at springs 260 and 263, including the leftha-nd .windlngof electropolarized relay 200, 'the .secondary windings of the operators in'ductioncoil,

the associated resistance, andthe impulse springs of the calling device S The conductors 250 and 251 extend, by way of the normally closed contacts controlled by armatures 21-3 and 214, to the upper and lower windings of line relay-203 ofthe test distributor selector repeater. D. The upper zwindin'g of line relay 203 :is'connected ,to

battery, while the lower winding; extends to ground, by way of the normally, closed contacts controlled byspring211, and accordingly; the said relay energizes. Electropolarized relay 200, however, associatedwith the operators headset, is not'energized' at this time, owing to the fact that the current flowing in its lett=hand winding is in aidir'ection opposite to that in which it'must flow in order to energize the said relay; Linere- This is due to the fact that the wiper 135 of switch F, which corresponds to wiper lay 203, upon energizing, closes a circuit for opens a point in the circuit of the release magnet 224' and closes a point in the circuit of the verticalmagnet' 222 at armature 220 and at armature 219 closes a circuit for the left hand or .polari-zir ilglgwinding of electropolarized relay 201.. 'isrelay' also is identical with relay 7, Fig. 1, and accordingly does ,5

not operate at this time.

The operator rnayv now inanipu'late her calling device S in accordance with thefirst test contact 96 1n the bank of the test disdigit of the'desired number whereupon the line relay 203 is de'e'n'ergized a correspond ing number of times and, u on'each deen--' ergization, completes the fol owing circuit:

from ground by way ofi armature 216 and its resting contact:ofarniature 231 andsaid" armature, and verticalxmagnet 222- to b'attery. By the operation of-the vertica'lmagnet, the shaft and wipers" are raised step by step .until the latter-stand O'ppbsitethedesired level of bank contacts,,a*ssum ed in this case to be the level in which the trunk line comprising conductors 32-36, inclusive", terminates. Relay 206- is energlzed ln-series with'the vertical magnet and being slowfacting retains its armatures attracted throughout :the vertical movement; 'By; thejoint operation of armature 221 and the otE-normal contacts 226,- which close upon the first vertical step, a circuit isclosed. for the stepping relay 207. Upon energizing, relay 307 prepares a'cir'cuit for the rotary .magnet 223*at armature-227 and at armature-1228 contact ofarma'ture 252 and the said armature, workingcontact of armature'228 and said armature, resting, oontactof the armayestablishesthe following locking circuit-for itself: from ground-by,- way of'theres'ting tical movement, relay 206 deenerglz-esand closes the circuit. of rotary. magnet 223. Upon energizing} magnet 223 steps; the wipers 240 to 244, inclusive, into engagement with the first set of contacts in the level'opposite which they are raisedpatthe same time opening the previously-described looking circuit of. stepping relayv 207. Relay .207 accordingly deenergizes and at armature 227 opens the circllii f the rotary. magnet? which deenergizes also and closes its interrupter contacts again. I

The operation now depends upon whether the trunk lineterminating in the first set of contacts is busy or idle. If it is busy 'level are busy, this alternate operation of the rotary magnet and stepping relay continues until the wipers 240-244, inclusive,

pass off the last set of contacts. The cam 212 is so placed and adjusted as to operate the springs 209-211, inclusive, whenever the shaft is rotated sufiiciently to cause the wipers to pass off the last set of contacts in the level. Spring 209, upon operating,

' opens the circuit of the switching relay 204 'sumethat all the trunk lines terminating so'as to prevent its energization at this'time.

Spring 210 upon operating closes a circuit for reversing relay 202 and the said reversing relay, upon energizing, reverses the line conductors 250 and 251 as regards their connection with the windings of line relay 203. This obviously reverses the flow of current in the said conductors and in the left hand winding of the electropolarized relay 200. Relay 200 energizes now and closes a circuit for the busy lamp L.

Returning now to the operation of the springs 209211, inclusive, thespring 211 upon operating shifts the circuit of the lower winding of line relay 203 so as to include the left hand winding of the transformer associated with the busy signalling machine B. As a result of this operation, the operator is given an audible busy signal in addition to the visual busy signal already described. Upon noting the busy signals, the operator may release the connection and call again later.

In the present case, however, we shall asthat level are not busy and that the trunk line terminating in bank contacts 245-249, inclusive, is the first one found idle. That being the case, when the wipers 240-244, inclusive, arrive upon the said contacts the switchingrelay 204, being no longer short circuited, energizes over the following circuit: from ground by way of armature 219 and its working contact, resting contact of spring209 and said spring, switching relay 204, resting contact of the armature of rotary magnet 223 and said armature, off normal contacts 226, and stepping relay 207,

to battery. Stepping relay 207 is not energized at this time, however, on account of its comparatively small number of turns and stiff adjustment. Upon energizing, re-

lay204 grounds the'test wiper 242 at armature 217 lso as'to make the seized trunk busy; opens a point in the circuit oftli'e vertical magnet 222, at armature 231; removes ground from the locking circuit of stepping relay 207 at armature 252; and at armature 218 places the following bridge across the operating conductors 34 and'35 of the seized trunk line: from conductor 35, by way of bank contact 248, wiper 243, armature 218 and its working contact, working contact of armature 215 and said armature,-

right hand winding of electro-polarized]relay 201, wiper 241, and bank contact 246, to conductor 34. Relays 41-43, inclusive, in

the test distributor E now energize-and prepare the switch for operation in the usual manner. Electropolarized relay 201,

however, does not energize at this time owing to the fact that the current is flowing in its right handwinding in the direction opposite to that in which it must flow in order to operate the said relay. It will be noted that busy lamp L as well as itsmulti pies in front of the other wire 'chiefs, is.

H, operates in the same manner in this call as it does when the wire chief makes a call, such as the one previously described. In case a busy signalling current is placed on conductor 35 by the test distributor E, it

flows back by way of armature 218 of switch 1) and its working contact, and condenser 264'to the lower winding of line relay 203,

and thence to the calling 'o-peratorshead set. In response to any reversal of current in conductors 35 and 36, the electropolarized relay 201 operates and closes the circuitfof reversing relay 202, thereby, finally giving the calling operator a visualbusy signal, as

hereinbefore described.

After having called the number, the operator is able to ascertain, lay-listening in, whether or not the line of substation A is busy; and, after obtaining the desired information, she restores the key K to normal position, thereby opening the circuit of the line relay 203 which, upon-deenergizing, opens the circuit of release relay 205.- Relay 20 5, upon deenergizing, opens'the' circuit of switching relay 204 at armature 219.

Relay 204, upon deenergizing, opens the bridge across the operating 'conductorsat armature 218 whereupon the switches E, F, and II restore to normal position, in the usual manner. As a further result of the operationpf releaserelaly 205, it closes the It is obvious that the test mo aim circuit o f release magnet-224;. 'By th'e op:- eration of the releasez' magnefi-tlie':-slraft and wipers are restored? tononrral position', 'tlh'e circuit of the said magnet being brlokenigat oft" normal contacts 225* by the-shaft, when it reaches normal position.

Having described' my invention, what I consider to be new and desire to have protected by Letters Patent will be pointed out in the appended claims.

hat I claim as my invention is:

1. In a wire chiefs testing system, a testing circuit comprising apparatus for testing subscribers lines, a series of automatic switches controlled from said test circuit to connect the same with a subscribers line, a marginal relay for controlling the release of one of said switches, a control circuit including said relay controlled by the wire chief, and means in said control circuit for preventing the release of another of said switches.

2. In a wire chiefs testing system, a testing circuit comprising apparatus for testing subscribers lines, a series of automatic switches controlled from said test circuit to connect the same with a subscribers line, a marginal relay in the first one of said switches for controlling the release of all the rest of said switches, another relay for controlling the release of the said first switch, and means in the said test circuit for controlling said relays separately.

3. In a wire chiefs testing system, a testing circuit comprising apparatus for testing.

subscribers lines, a series of automatic switches controlled from said test circuit to connect the same with a subscribers line, a relay in one of said switches for controlling the release thereof, a marginal relay for controlling the release of the rest of said switches, a common circuit including both relays, and means in the said test circuit for altering the current flow in said circuit to cause the deenergization of one relay independent of the other.

4. In a wire chiefs testing system, a testing circuit comprising apparatus for testing subscribers lines, a series of automatic switches controlled from said test circuit to connect the same with a subscribers line, a relay in one of said switches for controlling the release thereof, a marginal relay for controlling the release of the final switch, a common circuit including both relays, and means in said test circuit for reducing the current flow in said circuit enough to deenergize the said marginal relay while maintaining the other relay energized.

5. In a wire chiefs testing system, a series of automatic switches for connecting a test circuit at the wire chiefs deskwith a subscribers line to be tested, a line relay and a marginal relay in one of said switches,

a cincuit' =i1icl uding both relays, means at the w'irerchief s desk"for -varying*the currenti in -'said-21circuit't'o c'o'ntrol one of said? relays illdependently'of the other; and nel'ease mieans '6; a win-e chiefs-testing sys'tem;- a series of automatic switches for connecting a test circuit at the wire chiefs desk with a series of automatic switches for connecting a test circuit at the wire chiefs desk with a subscribers line to be tested, a circuit for energizing the cut-off relay of the subscribers line when the line is connected with, a marginal relay in one of said switches for closing said circuit, a line relay in the same switch, a common circuit including both relays, and means at the wire chiefs desk for varying the current in said common circuit to control said marginal relay independently of said line relay.

8. In a wire chiefs testing system, a series of automatic switches for connecting a test circuit at the wire chiefs desk with a subscribers line to be tested, a circuit for energizing the cut-off relay of the subscribers line when the line is connected with, a marginal relay in one of said switches for closing said circuit, a line relay in the same switch, a common circuit including both relays, and means at the wire chiefs desk for reducing the current flow in said common circuit to deenergize the said marginal relay independent of said line relay.

9. In a wire chiefs testing system, a series of automatic switches for connecting a test circuit at the wire chiefs desk with a subscribers line to be tested, a line relay and two marginal relays in one of said switches, a circuit controlled by one of said marginal relays for energizing the cut-off relay of the subscribers line when the line is connected with, releasing means in the final switch controlled by the other of said marginal relays, a common circuit including said line relay and both marginal relays, and means at the wire chiefs desk for varying the current in said common circuit to cause one or both of said marginal relays to deenergize independent of said line relay.

10. In a telephone system, a trunk line including two talking conductors, two serially related automatic switches for connecting said trunk line with a called subsubscribers line to be tested, a line relay lays in the final switch, one controlling the release of said switch and'the other: controlling the change overzfrom primary to secondary operation, and other-relays in the said first switch for exercising all other necoperated.

essary control over the final switch, including a relay for openin the said talking conductors while the sai final switch being '10 In witness whereof, I hereiinto "subscribe my name this 10th day-of May, A. D. .1921.

I CLARENCE E.- 

